wroksheet

Jasmine_Lr

Chapter2.pptx

Home >Business & Finance homework help >Management homework help >wroksheet

CHAPTER 2

Nutrients: Ingestion to Energy Metabolism

What happens to nutrients after they are ingested?

Digestion

Mastication

Enzymatic activity

Absorption

Transport

Assimilation and/or energy production

Digestion: Anatomy and Functions of the Digestive System

Mouth (oral cavity)

Esophagus

Stomach

Small intestine

Large intestine

Rectum

Figure 2.1 Anatomy of the digestive system.

Digestion: Salivary Glands

Salivary glands

Parotid

Sublingual

Submandibular

Secrete saliva

Moistens food

Contains enzymes

Figure 2.3 The salivary glands. The three pairs of salivary glands supply saliva, which moistens and lubricates food. Saliva also contains salivary enzymes that begin the digestion of starch.

Digestion: Stomach

Muscular organ

Primary function: Digestion

Major secretions

Hydrochloric acid

Mucus

Digestive enzymes

Digestion and Absorption: Small Intestine

Duodenum

Majority of digestion occurs here

Jejunum

Little digestion

Absorption

Ileum

Absorption

Figure 2.4 The small intestine. Secretions from the pancreas, liver, and gallbladder assist in digestion. All along the intestinal walls, nutrients are absorbed into blood and lymph. Undigested materials are passed on to the large intestine.

Absorption: Surface of Small Intestine

Convoluted interior

Villi

Microvilli

Result: Increased surface area for absorption

Figure 2.5 The absorptive surface of the small intestine. To maximize the absorptive surface area, the small intestine is folded and lined with villi. You have a surface area the size of a tennis court packed into your gut.

Absorption: Large Intestine

Colon

Ascending

Transverse

Descending

Rectum

Anus

Some absorption

Water – Potassium

Sodium – Vitamin K

Chloride

Figure 2.6 The large intestine. In the large intestine, bacteria break down dietary fiber and other undigested carbohydrates, releasing acids and gas. The large intestine absorbs water and minerals and forms feces for excretion.

Absorption of Nutrients

Figure 2.7 Absorption of nutrients.

Absorption: Mechanisms

Passive diffusion

Facilitated diffusion

Active transport

Endocytosis

Figure 2.8 Mechanisms for nutrient absorption. (A) Passive diffusion. Using passive diffusion, some substances easily move in and out of cells, either through protein channels or directly through the cell membrane. (B) Facilitated diffusion. Some substances need a little assistance to enter and exit cells. The transmembrane protein helps out by changing shape. (C) Active transport. Some substances need a lot of assistance to enter cells. Similar to swimming upstream, energy is needed for the substance to penetrate against an unfavorable concentration gradient. (D) Endocytosis. Cells can use their cell membranes to engulf a particle and bring it inside the cell. The engulfing portion of the membrane separates from the cell wall and encases the particle in a vesicle.

Carbohydrates: Digestion

Mouth

Mastication

Amylase

Stomach

Churning

Acid

Small intestine

Sugar enzymes

Large intestine

Bacteria

Figure 2.12 Triglyceride digestion. Most triglyceride digestion takes place in the small intestine.

Carbohydrates: Absorption

Most absorption occurs in small intestine.

Mechanisms

Facilitated diffusion: Fructose

Active transport: Glucose and galactose

Carbohydrates: After Absorption

Transport via blood

Cellular uptake

Insulin

Glucose transporters

Fates

Storage

Conversion

Energy

Figure 2.9 Flow chart of glucose and other simple sugars immediately after a meal.

Fats: Digestion

Mouth

Mastication

Lingual lipase

Stomach

Gastric lipase

Small intestines

Bile

Pancreatic lipase

Micelle formation

Fats: Absorption

Occurs in small intestine

Mechanism

Passive diffusion

Very little fat makes it to large intestine

Steatorrhea

Crohn’s disease

Cystic fibrosis

Figure 2.13 Summary of lipid absorption.

Fats: After Absorption

Transport

Lymph

Chylomicrons

Blood

Cellular uptake

Lipoprotein lipase

Fates

Storage

Energy

Proteins: Digestion

Mouth

Mastication

Stomach

Churning

Acid denaturation

Small intestine

Proteases

Peptidases

Proteins: Absorption

Occurs in small intestine

Mechanisms

Facilitated diffusion

Active transport

Very little makes it to large intestine

Proteins: After Absorption (1 of 2)

Transport

Blood

Become part of amino acid pool

Fates

Body proteins

Conversion

Energy

Proteins: After Absorption (2 of 2)

Figure 2.16 Amino acid pool turnover. Cells draw upon their amino acid pools to synthesize new proteins. These small pools turn over quickly and must be replenished by amino acids from dietary protein and degradation of body protein. Dietary protein supplies about one-third, and the break-down of body protein supplies about two-thirds of the roughly 300 grams of body protein synthesized daily. When dietary protein is inadequate, increased degradation of body protein replenishes the amino acid pool. This can lead to the breakdown of essential body tissue.

Cellular Protein Synthesis

Transcription

DNA

mRNA

Translation

Transfer RNA

Amino acids

Figure 2.17 Protein synthesis. Ribosomes are our protein-synthesis factories. First, mRNA carries manufacturing instructions from DNA in the cell nucleus to the ribosomes. Then tRNA collects and delivers amino acids in the correct sequence.

Digestion causes release from foods.

Absorption occurs in small and large intestines.

Vitamins, Minerals, and Water

What is energy?

It is the entity that enables our bodies to perform work.

It has no shape.

It has no physical mass.

Our bodies rely on chemical energy.

What is the body’s source of energy?

Macronutrients

Carbohydrates

Fats

Proteins

Body’s direct energy source

Adenosine triphosphate (ATP)

Figure 2.19 The ADP–ATP cycle. When extracting energy from nutrients, the formation of ATP from ADP + Pi captures energy. Breaking a phosphate bond in ATP to form ADP + Pi releases energy for biosynthesis and work.

Adenosine Triphosphate (ATP)

Body’s energy source

Two high-energy bonds

Other phosphates

ADP

AMP

Figure 2.20 ATP, ADP, AMP, and high-energy phosphate bonds. Your body can readily use the energy in high-energy phosphate bonds. During metabolic reactions, phosphate bonds form or break to capture or release energy.

Cell Structure and Organelles Necessary for ATP Production

Figure 2.22 Component parts of a typical cell.

What are the three energy systems?

Phosphagen system

Anaerobic energy system

Aerobic energy system

Comparison of the Three Energy Systems

Metabolic Pathways

Energy Nutrients

Cellular ATP Production: The Metabolic Factory

Figure 2.23 Metabolic factory analogy of energy metabolism.

Phosphagen Energy System

Stores of high-energy phosphates

ATP

Creatine phosphate (CP)

Also known as:

Immediate energy system

ATP-CP system

Figure 2.24 The ATP–CP energy system. To maintain relatively constant ATP levels during the first few seconds of a high-intensity activity, creatine phosphate releases energy and its phosphate (Pi) to regenerate ATP from ADP.

Anaerobic Energy System

Involves only carbohydrates

Does not require oxygen

Also known as:

Anaerobic glycolysis

Figure 2.29 Anaerobic glycolysis.

Aerobic Energy System

Involves all macronutrients

Requires oxygen

Also known as:

Oxidative system

Figure 2.30 Aerobic metabolism of the macronutrients.

Carbohydrate Intake Impacts Protein Metabolism

Carbohydrates are an important energy source.

Low carbohydrate intake can result in muscle protein breakdown and loss of muscle mass.

Gluconeogenesis forms glucose from proteins.

Adequate carbohydrate intake spares muscle mass.

Figure 2.35 Gluconeogenesis. Liver and kidney cells make glucose from pyruvate by way of oxaloacetate. Gluconeogenesis is not the reverse of glycolysis. Although these pathways share many reactions, albeit in the reverse direction, gluconeogenesis must detour around the irreversible steps in glycolysis.

Energy System Contributions to Activities of Varying Intensity (1 of 5)

The small storage pool of ATP is the source of energy whenever instantaneous energy is needed.